Transistorized ignition system with a bistable electromagnetic switch



p 1964 F. MIERAS TRANSISTQRIZED IGNITION SYSTEM WITH A BISTABLEELECTROMAGNETIC SWITCH Filed Jan. 31, 1962 LAURENCE E M/ERAS INVENTORUnited States Patent This invention relates to an ignition syst m for aninternal combustion engine and more particularly to a transistorizedignition system for an internal combustion engine.

In conventional internal combustion engine ignition systems, fullbattery voltage is applied across the primary winding of the ignitioncoil through a set of distributor breaker points. As a result, a heavycurrent flows in the primary winding and through the breaker points.When the breaker points are opened, arcing occurs across the pointssince current through the primary winding continues to flow because ofthe collapsing magnetic field of the ignition coil. This causes pittingand corrosion of the breaker points and experience shows that thebreaker points have to be periodically replaced because of this pittingand corrosion.

The present invention provides an igition system in which pitting andcorrosion of the breaker points are substantially reduced. This isaccomplished by employing a transistor circuit in which the primary ofan ignition coil is positioned in the load circuit of the transistor andin which a pair of distributor breaker points are positioned in the baseor control circuit of the transistor to alternately turn the transistoron and 05. Thus, the breaker points switch only base or control circuitcurrent which is substantially less than the primary current which mustbe switched by conventional ignition systems.

It is Well known that the voltage induced in the secondary of anignition coil is proportio l to the time rate of change of the flux inthe coil and that peak outputs occur when the magnetic field in the coilcollapses due to change primary current as the switching means in theprimary circuit is opened. It follows, therefore, that high secondarywinding outputs will occur it short switching times for the primer"currer s can be accomplished.

The present invention provides a circuit for reducing switching times intransistorized ignition systems by employing means that causes a reversecurrent to flow in the base-emitter circuit of the transistor when thedistributor breaker points are opened. This reverse current causes thetransistor to be rapidly cut oif and it, therefore, rapidly interruptscurrent flow through the primary winding of the ignition coil. As aresult, high secondary output voltages are obtained from the secondarywinding of the ignition coil. The means referred to above may take theform of an electromagnetic switch including a core constructed offerromagnetic material. This ferromagnetic core is magnetized in onedirection when the transistor is in its conducting state. When thedistributor breaker points are opened, the ferromagnetic core isswitched from one direction of magnetization to the other direction ofmagnetization. An output winding is wound upon this ferromagnetic coreand is connected to the base and to the emitter of the transistor. Thisoutput winding applies a pulse of electrical energy to the base of thetransistor of a polarity opposite to the polarity of the bias applied tothe base to cause the transistor to conduct thereby causing a pulse ofreverse current to flow th ough the base and the emitter for a veryshort period of time. As a result, the uansistor is rapidly switchedfrom its conducting to its nonconducting state.

As will be more fully explained in the main body of the specification,the transistorized ignition system of this invention will operate verywell at low engine speeds such as occur during engine crankingconditions. This is brought about by the fact that the ferromagneticcore can be switched from one state of magnetization to the other stateof magnetization even though the distributor breaker points are slow toopen or may not open completely.

Although the invention was discussed above in relation to a pair ofdistributor breaker points being positioned in the base circuit of thetransistor to periodically interrupt current flow therethrough, it isobvious that various other means for interrupting the base current maybe employed. For example, a magnetic switch that includes a windingpositioned in series with the base circuit and a multipole permanentmagnet driven by the distributor and placed adjacent this winding mayalso be employed.

An object of the invention is the provision of a transistorized ignitionsystem for an internal combustion engine.

Another object of the invention is the provision of a transistorizedignition system for an internal combustion engine in which thetransistor is cut off very rapidly when it is desired to interrupt thecurrent in the primary windings of ignition coil.

A further object of the invention is the provision of a transistorizedignition system for an internal combustion en ine that will work verywell and will provide proper ignition at low engine speeds.

Still another object of the invention is the provision of atransistorized system for an internal combustion engine that includesmeans for causing a reverse current to flow in the base-emitter circuitof the transistor when it is desired to interrupt current in the primarywinding of the ignition coil, thereby rapidly switching the transistorfrom its conducting to its nonconducting state.

(Ether objects and attendant advantages of the present invention willbecome more readily apparent as the specification is considered inconnection with the accompanying drawings in which:

FIG. 1 is a circuit diagram of one embodiment of the invention;

FIG. 2 is a partial circuit diagram of another embodient of theinvention;

FIG. 3 is a wiring diagram of the ferromganetic core employed in theembodiments shown in FIGS. 1 and 2;

FIG. 4 is a hysteresis loop of the ferromagnetic core shown in PEG. 3;

FIG. 5 is a plot of the pulse of reverse current that flows through thebase-emitter circuit of the transistor, with the Y axis showing themagnitude of the current how and the X am's being a time base inmicroseconds, and,

FIG. 6 is a schematic representation of the transistor during the timethat reverse current flows in the baseernitter circuit of thetransistor.

Referring now to the drawings in which like reference numerals designatelike parts throughout t e several views thereof, there is shown in FIG.1 a transistorized ignition system that may be employed with anautomotive vehicle internal combustion engine. This ignition systemincludes a transistor it having an emitter 11, a collector i2 and a base13. For purposes which will be more fully developed later in thespecification, the transistor i is preferably of the type that has a lowbreakdown volta e between the emitter and base when a reverse bia is appd between the emitter and base. A breakdown voltage in the range of 1 to5 volts is satisfactory, and a diffused alloy power transistor having agraded or din' used base provides this characteristic.

the ignition switch is in the off position.

An electromagnetic switch means is connected in circuit with thetransistor 10. This electromagnetic switch means includes aferromagnetic core 16 constructed of a material having a'square orrectangular type hysteresis loop and having a fast switching time. ADeltarnax material which is a grain orientated 50 percent nickelironalloy having a rectangular hysteresis loop may be employed to constructthe ferromagnetic core 16. A first input winding 17 is wound upon thecore and has one end connected through a lead 18 to the base 13 oftransistor 10. The other end of the first input winding 17 isconnected-by a lead 21 to aresistor 22. A second input winding 25 iswound upon the core 16 and is connected at one end through a lead 26 tothe collector 12 of transistor 10. The other end of the second inputwinding 25 is connected through a lead 27 to a junction point 28. Anoutput winding 31 is wound upon the ,core 16 and has one end connectedto the base 13 of transistor 10 through a lead 32.

output winding 31 is connected through a lead 33 to a The other end ofthe resistor 34. The resistor 34 is in turn connected to the emitter 11of transistor 10 through a lead 35.

the positive terminal 41 of battery 42 through leads 47 and 43; Theignition switch 43 includes six contacts,

designated by the numerals 51 through 56. .The contact 52 is connectedto resistor 44 through leads 57 and 58,

while the contact 53 is connected to resistor 44 through lead 59 andlead 58. The contact 56 is connected to "the emitter 11 of thetransistor 10 through leads 61 and 62, while the resistor 44 isconnected to the emitter 11 through a lead 63 and lead 62.

' When the movable ganged arms 45 and 46 of ignition switch 43 areconnected'to contacts 51 and 54 respectively, When the arms 45 and 46are in contact with the contacts 52 and 55 respectively, the ignitionswitch is in the on position and current is fed from the positiveterminal of the battery 41 to the emitter 11 of transistor 10 throughlead 47, movable arm 45, contact 52, lead 57, lead 58, resistor 44, lead63 and lead 62. When the movable ganged arms 45 and 46 of ignitionswitch 43 are in contact with contacts 53 and 56 respectively, theignition is in the start position and electrical energy is fed from thepositive terminal 41 of the battery 42 to the emitter 11 0f transistor10 through lead 47, lead 48, movable arm 46, contact 56, lead 61 andlead 62. Thus, when the ignition switch is in the start position, theresistor 44 is bypassed so that more energy wih be fed to the transistor10 during starting operations than is fed to its during ordinaryoperating conditions.

As previously described, the resistor 22 is connected to the base 13 oftransistor 10 through lead 21, input winding 17 and. lead 18. The otherend of the resistor a resistor 70. The other end of the primary winding71 is grounded through a lead 73. The secondary Winding 74 of theignition coil 72 is connected through lead 75 with rotating arm 76 ofdistributor 77. The other end of the secondary winding 74 is groundedthrough a lead 78. The rotating arm 76 sequentially connects thesecondary winding 74 of the ignition coil 72 with .spark' plugs 81through 86 by means otdistributor cap conand to the lead 73 so that itis connected across the series combination of the primary winding 71 andthe resistor 70. This capacitor functions to reduce the instantaneousWattage appearing across the transistor 10 when the tran-. sister isswitched from its conducting to its nonconducting state. A zener diode98 is connected across the transistor between the emitter 11 and thejunction point 28 to protect the transistor from voltages in excess ofthose at which it is designed to operate. This zener diode will have abreakdown voltage substantially equal to the voltage at which thetransistor 10- is designed to operate. Voltages of a magnitude'in excessof the peak voltage that the transistor can Withstand may appear whenthe transistor is switched from its conducting to its nonconducthigstate due to the inductive kick from the primary winding 71 of ignitioncoil 72. When this occurs the zener diode 98 will break down and willprovide a low resistance path in parallel with the collector and theemitter of the transistor.

FIG. 2 discloses another embodiment of the invention in which the secondinput winding 25 is connected across the'termina1s41 and 68' of theelectrical storage battery 42 rather than being connected in series withthe emitter 12 of transistor 10 and the resistor 70 and primary winding71 of the ignition coil 72. ,In FIG. 2, one end of the second inputwinding 25 is connected to ground through a lead 101 while the other endof the first input winding 25 is connected through a lead 102 to aresistor 103. The other end of the resistor 103 is connected through alead 184 to the lead 62.

The emitter 11 and the collector 12 of the transistor 16 may properly betermed output terminals, while the base 13 and the emitter 11 may betermed input terminals.

properly termed an input or control circuit.

The ignition systems shown in FIGS. 1, 2 and 3, may

employ the following components which are givenv by 'way of exampleonly:

Transistor 10 2N1073B.

Core 16 An Arnold Engineering Deltamax core3T8043D4. This core isconstructed of a grain oriented 50 percent nickeliron alloy having arectangu lar hysteresis loop. It may be wound from a strip of thismaterial having a thickness of .004 inch, and the core may have an innerdiameter of 0.500 inch and an outer diameter of 0.625

' inch. 7 Y First input winding 17 50 turns of copper wire.

.Second input winding 7 25 1 turn of copper wire. Output winding 31 10turns of copper wire.

Resistor 22 '8 ohms;

Resistor 34 5.6 ohms. Resistor 44 a 0.33 ohm. Resistor 70 0.43 ohm.Primary Winding 71 of igp, nition coil 72, turns of #17 copper wire.

Secondary winding 74 of ignition coil 72 26,600 turns of #38 copperwire.

Storage battery 42 A standard 12 volt automotive vehicle storagebattery.

Zener diode A; lN3G-S4A, having a breakdown voltage of 91 volts.

Resistor 1G3 1.00 ohm.

In operation of the ignition system shown in FIGS. 1 and 2, the operatorof the automotive vehicle in which it has been installed, moves theignition switch 43 to the start position in w ich the movable arms and46 are in engagement with contacts 53 and 55. After the internalcombustion engine has started, the ignition switch is moved to the onposition in which the movable arms 45 and 45 are positioned inengagement with the contacts 52 and 55. With the switch in the startposition, the emitter 11 of the transistor it; is directly connected tothe positive terminal 41 of storage battery 2-2 through the ignitionswitch 43. V/ith the ignition switch 4-?) in the on position, theemitter 11 will be connected to the positive terminal 41 of the storagebattery 42 through the ignition switch 43 and the resistor 44. On theother hand, the base 13 is connected to the negative terminal 63 ofstorage battery 42 through the lead 18, first input winding 17, lead 21,resistor 22-, distributor breaker points 61$, lead 67 and lead 69. Thiswill turn the transistor to its on position or conducting state when thedistributor breaker contacts as are closed. As a result, base currentwill iiow through the first input winding l7 positioned on core 16. Thecurrent that flows from the battery 42 through the transistor in to theprimary winding 71 of the ignition coil 72 flows through the secondinput winding 25.

Under ordinary operating conditions, the base current traversing thewinding 1'7 is approximately 1 ampere and since this windhig comprises56 turns, it will impress a magnetomonve force on the coil or" ampereturns. The current that normally flows from the transistor ll? to theprimary winding 71 is on the order of 12 amps and since this windingcomprises one turn, it will impress a magnetomotive force ofapproximately 12 ampere turns upon the core 16.

As can be seen by reference to PEG. 3, the first input winding 17 iswound to create a clockwise flux in the core and the second inputwinding 25 is wound to create a counterclockwise fiux in the core. Theresultant of these two magnetomotive forces is a maguetomotive force ofapprox mately 38 ampere turns which creates a resultant flux in the core16 in a clockwise direction. Referring to FIG. 4, this flux isdesignated as having a negative direction and the core described above,such as the Arnold 3T8043D4, is designed to saturate with magnetornotiveforce of approximately 6 ampere turns impressed upon it. It can be seen,therefore, that when current flows through both the first input winding17 and the second input winding 25 that the core 16 is saturated in thenegative direction.

During the time that the transistor is turned on, or is in itsconducting state, as a result of the distributor contact points beingclosed, the core 16 wfil be in a state of negative saturation. As aresult, the impedance of the output winding connected between the base13 and the emitter ii of transistor ll? will be substantially zero. Theresistor 34, however, provides sufficient resistance between the emitter11 and the base '13 of transistor It) to maintain proper o erat'uigbias. When the breaker points 65 are opened, the current through thefirst input winding 17 is interrupted or substantially reduced to zeroduring normal operating conditions. The transistor 19 will, therefore,tend to be turned to its nonconducting state. it has, however, a largeinductive element, primary winding 71 of ignition coil '72, connected inseries with it. Oarrent will continue to flow, therefore, through thetransistor it? for a short interval of time.

This current also traverses the second input winding 25 and since it hasa magnitude of approximately 12 amperes, it will switch the core fromits negative state of saturation to its positive state of saturation ina very rapid switching action. As a result of the switching of the core,a voltage is induced in the output winding 31. This voltage is of apolarity to cause a reverse current to flow in the base-emitter circuitof the transistor. Since in normal operation of the transistor currentflows from the emitter to the base, this reverse current flows from thebase to the emitter. It can be appreciated that the polarity of thevoltage applied to the base 13 by output winding 31 is opposite to thepolarity of normal operating bias.

It has been found that the voltage induced in the output winding 31 as aresult of the switching of the core 36 is approximately 5 volts. This issufiicient to cause a breakdown in the base to emitter junction of thetransistor it; and to cause a pulse of current through the base-emittercircuit including the winding 31 and the resister 34 of a peak magnitudeof approximately 1 am ere. Referring now to FiGS. 5 and 6, it can beseen that this current pulse has a very steep wave front. Tests haveshown that the current reaches a maximum or approximately one ampere andapproximately of a microsecond, and that it decays to approximately A ofan ampere in a range of from 6 to 8 microseconds fi ter the core 16 hasstarted to switch. As shown in FIG. 6, this current flows in acounterclockwise direction in the base-emitter circuit and thus it flowsin a direction that is the reverse of ord nary current flow in thetransistor when the transistor is in its conducting state.

This reverse current very rapidly switches the transistor 1% from itsconducting to its nonconducting state since the peak value of thiscurrent is reached in approximately A of a microsecond. it has beendetermined that the transistor can be turned ofi in the range of from 3to 6 microseconds using the circuit of the present invention. This willprovide high output voltages from the secondary winding '74; of theignition coil 72 since the current through the primary winding '71 israpidly cut oil. When this current is cut oil, the collapsing magneticfield of the primary winding 71 induces a high voltage in the secondarywinding 7 which is applied to one of the spark plugs 31 through 86 .131means of the rotating arm 7d and one or the distributor cap contacts 91through as. After this takes place, the distributor breaker points aswill again close to complete the base or input circuit of transistor it?and to bring the transistor is? into conduction.

Referring now to FIG. 4, it can be appreciated that the core in ismagnetized in a negative direction when the distributor breaker points66 are closed and current is flowing in the first input winding 17. Thenegative direction of magnetization corresponds to a counterclockwisedirection shown in FTG. 3. When the distributor breaker points so open,it will be apparent that the core at? is switched to a positivedirection of magnetization (corresponding to a clockwise direction inFIG. 3). When the distributor breaker points 66 open and the core 16 isswitched from its negative to its positive state of magnetization, theoutput winding 31 provides a pulse of electrical energy having apolarity to drive a pulse of reverse current through the baseemittercircuit of the transistor. This rapidly switches the transistor 1% fromits conducting to its nonconducting state. The core 15 will remain in apositive state of magnetization with a hut-r density at least equal tothe remnant flux density of the core unti the distributor breaker points6-5 close. At this time, the base current will again flow through thefirst input winding 17 and the core 15 will be switched to its negativestate of magnetization. The cycle described above is repeatedperiodically so that transistor is altemately switched from itsconducting state to its nonconducting state. Each time the transistor 10is switched to its nonconducting state, the rotating arm 76 comes intocontact with enact the distributor cap contacts 91 through 96 to supplya spark to one of the spark plugs 81 through 86.

The embodiment of the invention shown in FIG. 2 operates insubstantially the same manner as the embodiment of FIG. 1 except thatcurrent continuously flows through the second input winding 25 by way oflead 104, resistor 103, lead 162 and lead 101. Thus, the core 16 iscontinually biased towards a direction of positive magnetization by themagnetomotive force developed by the current in the first input winding25. When the distributor breaker points 66 are closed, current will flowin the first input winding 17, and this current will develop sufiicientmagnetomotive force to overcome the magnetomotive force developed by thecurrent flowing in the second input winding 25, so that the core will bepositioned in a state of negative magnetization. When the distributorbreaker points 66 open, the core will be switched from its negative toits positive state of magnetization and will remain in the positivestate of magnetization during the interval that the breaker points areopen. When the breaker points are again closed, the core will thenswitch back to its negative state of magnetization. The currents flowingin the first input winding 17 and the second input winding 25 of theembodiment shown in FIG. 2 are substantially the same as those of theembodiment shown in FIG. 1. As a result, the output voltage of outputwinding 31 and the reverse current flowing through the base-emittercircuit of transistor are substantially the same as those of theembodiment shown in FIG. 1.

In all of the embodiments of the invention, there is provided a veryreliable transistorized ignition system in which breaker point life issubstantially increased over conventional systems, since the breakerpoints need only switch the base current of the transistor rather thanfull primary current. V

This system will work very well at low engine speeds such as encounteredin engine cranking conditions. Dur ing low engine speeds, the breakerpoints 66 may be slow to open or will not open completely. In such acase, however, the core 16 of the ignition system will still switch fromone state of magnetization to the other since as the breaker points 66commence to open, the resistance of the base circuit will rise veryrapidly and the current through the base circuit and the first inputwinding 17 will be substantially reduced. Since the core can be drivento saturation by a magnetomotive force of around 6 ampere-turns, it canbe seen that the core will switch when the magnetomotive force impressedupon the core by the first input winding 17 falls to the neighborhood of6 ampere turns. Thus, the system will operate efficiently even thoughthe distributor breaker points are slow to open or'even though thedistributor breaker points fail to open completely.

The provision of the ferromagnetic core 16 with the very rapid switchingtime, in the neighborhood of a fraction of a microsecond, providesadvantages over other types of feedback systems that derive a feedbackpulse from a feedback winding coupled to the ignition coil itself. Sucha feedback winding cannot apply a feedback pulse to the transistor atsuch a rapid rate since the maximum voltage output from such a feedbackwinding occurs only when the flux change in the ignition coil reaches amaximum. This may take a period of time of the order of severalmagnitudes larger than the time required to switch the ferromagneticcore16. As previously stated,

f type transistor, the invention is in no way limited to this type oftransistor. It will be readily apparent to those skilled the art how thecircuit of the invention may be fconnected to employ other typesoftransistors, for example, a n.p.n. type transistor; Similarly, inventionmay employ any type of ferromagnetic core' that hasa substantiallyrectangular hysteresis loop and that will switch very rapidly under lowmagnetomotive forces.

It will be understood that the invention is not to be limited to theexact construction shown and described, but that various changes andmodifications may be made without departing from the spirit and scope ofthe invention as defined in the appended claims.

I claim:

1. An ignition system for an internal combustion engine comprising, aspark plug, an ignition coil including a primary winding and a secondarywinding, said secondary winding being connectable to said spark plug, asource of electrical energy, a transistor having an emitter, a collectorand a base, said primary winding of said ignition coil, said source ofelectrical energy and said collector and emitter of said transistorbeing connected in series, means connecting said base of said transistorwith said source of electrical energy for properly biasing saidtransistor, means connected in circuit with the base of said transistorfor interrupting current flow through said base, a ferromagnetic core,means connected in circuit with said transistor and said source ofelectrical energy for switching said ferromagnetic core from onedirection of magnetization to the other direction of magnetization inresponse to the interruption of current flow through said base, anoutput Winding wound upon said ferromagnetic core and connected to saidemitter and said base, said outputwinding being Wound upon saidferromagnetic core in a direction to cause a current to flowthrough'said emitter and base in a direction opposite to current flowthrough the base and the emitter when said transistor is in a conductingstate whereby said transistor is brought rapidly to its nonconductingstate.

2. An ignition system for an internal combustion engine comprising, aspark plug, an. ignition coil including a primary winding and asecondary winding, said secondary winding being connectable to saidspark plug, a source of electrical energy, a transistor having anemitter, a collector and a base, said primary winding of said ignitioncoil, said source of electrical energy and said collector and emitter ofsaid transistor being connected in series, means connecting said base ofsaid transistor with said source of electrical energy for properlybiasing said transistor, means connected in circuit with said base ofsaid transistor for interrupting current flow through said base,

.a ferromagnetic core having a substantially rectangular hysteresisloop, a first input winding wound upon said ferromagnetic core, saidfirst input winding being connected in circuit with said base and withsaid'means for interrupting current flow through said base wherebynormal operating base current flows through said first input Winding, asecond input winding wound upon said ferromagnetic core, said secondinput winding being connected in circuit with said source of electricalenergy, the magnetmotive force developed by the current in said firstinput winding being suflicient to magnetize the ferromagnetic core inone direction, the magnetomotive force developed by the current in thesecond input winding being sufiicient to magnetize the ferromagneticcore in the other direction, the resultant magnetomotive force of saidfirst input winding and said second input winding magnetizing said corein said one direction, said ferromagnetic core switching from onedirection of magnetization to the said other 'tion opposite to thenormal current flow through said base and emitter when said magneticcore is switched as aresult of current being interrupted in said baseand said first input winding, whereby said transistor is switched;rapidly from its conducting to its nonconducting state.

3. In an ignition system foran internal combustion engine thecombination comprising a plurality of spark plugs, an ignition coilincluding a primary Winding and a secondary winding, a distributor forsequentially connecting said secondary winding with said spark plugs, asource of electrical energy, a graded base transistor having an emitter,a collector and a base, said primary winding of said ignition coil beingconnected to said collector, said distributor including a pair ofbreaker points, said emitter being connected to said source ofelectrical energy and said base being connected to said source ofelectrical energy through said breaker points, a ferromagnetic corehaving a substantially rectangular hysteresis loop positioned adjacentsaid transistor, a first input winding positioned upon said core andconnected in series with said base and said breaker points, a secondinput winding positioned upon said core and connected in series withsaid collector and the primary winding of said ignition coil, an outputwinding positioned upon said core and connected to said emitter and tosaid base, the resultant magnetomotive force of said first and secondinput windings being sufiicient to magnetize the core in one direction,the magnetomotive force developed by said second input winding beingsufficient to magnetize the core in the other direction whereby saidcore is switched from one state of magnetization to the other state ofmagnetization when said breaker points are opened, said output windingbeing wound upon said core in a direction to produce a current flowthrough said base and said emitter in a direction opposite to the normalcurrent fiow through said base and said emitter whereby said transistoris rapidly brought to its nonconducting state when said breaker pointsare opened.

4. In an ignition system for an automotive vehicle the combinationcomprising a plurality of spark plugs, an ignition coil including aprimary winding and a secondary winding, a distributor for sequentiallyconnecting said secondary winding with said spark plugs, a source ofelectrical energy, a transistor having input terminals and outputterminals, an input circuit connected to said input terminals and anoutput circuit connected to said output terminals, said primary windingof said ignition coil being positioned in the output circuit of saidtransistor, said distributor including a pair of breaker points, saidsource of electrical energy and said pair of breaker points beingconnected in series and positioned in the input circuit of saidtransistor, and a bistable electromagnetic switch means positionedadjacent said transistor, said bistable electromagnetic switch meanscomprising a ferromagnetic core having a substantially rectangularhysteresis loop, a first input winding wound upon said ferromagneticcore and connected in the input circuit of said transistor and in serieswith said breaker points, a second input winding wound upon said coreand connected in series with the primary winding of said ignition coil,the resultant magnetomotive force developed by said first and saidsecond input windings being suificient to magnetize the core in onedirection, the magnetomotive force developed by said second inputwinding being suificient to switch the core to its other direction ofmagnetization when current fiow through said first input winding isinterrupted due to the opening of said breaker points, and an outputwinding wound upon said core and connected in circuit with the inputterminals of said transistor for causing a current to flow through saidinput terminals in a direction opposite to current flow through saidinput terminals during normal operation.

5. In an ignition system for an automotive vehicle the combinationcomprising a plurality of spark plugs, an ignition coil including aprimary winding and a secondary winding, a distributor for sequentiallyconnecting said secondary winding with said spark plugs, a source ofelectrical energy, a transistor including a collector, an emitter, and abase, said primary Winding being connected in series with saidcollector, said emitter and said source of electrical energy, Said basebeing connected to said 10 source of electrical energy for biasing saidtransistor to its conducting state so that current flows through saidbase to said source of electrical energy, a bistable ferromagnetic core,a first input winding wound upon said ferromagnetic core and connectedin series with said base, a second input winding wound upon said coreand connected in series with the prirnary winding of said ignition coil,the resultant magnetomotive force of said first and said second inputwindings being sufficient to magnetize said core in one direction whensaid transistor is in its conducting state, and means positioned inseries with said base and said first input winding and driven by saiddistributor for interrupting current flow through said base and saidfirst input winding, the current flow through said second input windingbeing sufficient to switch the ferromagnetic core to the other directionof magnetization, and an output winding connected to the emitter and thebase of said transistor and wound upon said core in a direction toproduce a current fiow through said base and said emitter upon thechange of direction of magnetization of said ferromagnetic core in adirection opposite to the current flow when said transistor is in aconducting state.

6. An ignition system for an internal combustion engine comprising, anelectrical ignition means, an ignition coil including a primary and asecondary winding, said secondary winding being connected in circuitwith said electrical ignition means, a source of electrical energy, asemiconductor device having input terminals and output terminals, aninput circuit connected to said input terminals and an output circuitconnected to said output terminals, said primary winding of saidignition coil being positioned in the output circuit of saidsemiconductor device, means operable by the internal combustion enginefor periodically reducing current in the input circuit of saidsemiconductor device, a bistable electromagnetic switch, meanspositioned in the input circuit of said semiconductor device and coupledto said bistable electromagnetic switch for maintaining said bistableelectromagnetic switch in one of its stable states by normal currentflow through said input circuit of said semiconductor device when saidsemiconductor device is in its conducting state, means coupled to saidbistable electromagnetic switch and said source of electrical energy forswitching said bistable electromagnetic switch from its one stable stateto its other stable state when current in the input circuit of saidsemiconductor device is reduced, and means coupled to said bistableelectromagnetic switch and said input circuit of said semiconductordevice for causing a current to flow through said input circuit of saidsemiconductor device when said bistable electromagnetic switch isswitched from its one stable state to its other stable state in adirection opposite to the direction of current through said inputcircuit when said semiconductor device is in a conducting state.

7. An ignition system for an internal combustion engine comprising asource of electrical energy, an ignition coil including a primary and asecondary winding, a semiconductor device including an output circuitand an input circuit, said output circuit of said semiconductor deviceconnected in circuit with said source of electrical energy and saidprimary winding of said ignition coil for controlling the energizationof said ignition coil, an electrical ignition means, said electricalignition means connected in circuit with said secondary winding, abistable electromagnetic switch electrically coupled to said inputcircuit of said semiconductor device, means adapted to be operated bythe internal combustion engine and coupled to the input circuit of saidsemiconductor device for periodically switching said semiconductordevice to its nonconducting state, and circuit means coupled to saidbistable electromagnetic switch and said last mentioned means forswitching said bistable electromagnetic switch from one of its stablestates to the other of its stable states as said semiconductor device isswitched to its nonconducting state, and means coupled to saidbistableTelecconductor device including an output circuit and an inputcircuit, said output circuit of said semiconductor device connected incircuit with said source of electrical energy and said primary windingof said ignition coil for controlling the energization of said ignitioncoil, an electrical ignition means, said electrical ignition meansconnected in circuit with said secondary winding, a bistableelectromagnetic switch electrically coupled to said input circuit ofsaid semiconductor device, means adapted to be operated by the internalcombustion engine and coupled tothe input circuit of said semiconductordevice for periodie cally reducing current flow in the input circuit ofsaid semiconductor device, circuit means coupled to said bistableelectromagnetic switch and said last mentioned means for switching saidbistable electromagnetic switch from one of its stable states to theother of its stable states as the current flow in said input circuit ofsaid semiconductor device is reduced, and means coupled to said bistableelectromagnetic switch and the input circuit if said semiconductordevice for driving a current through said input circuit of saidsemiconductor device as said bistable electromagnetic switch is switchedfrom said one stable state to said other stable state in a directionopposite to the current flow through said input circuit when saidsemiconductor device is in a conducting state whereby said semiconductordevice is brought rapidly to its nonconducting state.

9. An ignition system 'for an internal combustion engine comprising, asource of electrical energy, an ignition coil including a primary and asecondary winding, a semiconductor deviceincluding an output circuit andan input circuit, said output circuit of said semiconductor deviceconnected in circuit with said source of electrical energy and saidprimary Winding of saidignition coil for controlling the energization ofsaid ignition coil, an electrical ignition means, said electricalignition means connected in circuit with said secondary winding, meansconnecting said input circuit of said semiconductor device with saidsource of electrical energy forrcausingsaid semiconductor device toconduit, means connected in circuit with said input circuit of saidsemiconductor device for reducing current flow in the input circuit ofsaid semiconductor device, a ferromagnetic core, means connected incircuit with said semiconductor device and said source of electricalenergy for switching said ferromagnetic core from one direction ofmagnetization to the other direction of magnetization in responseito thereduction of current flow in said input circuit of said semiconductordevice, an output Winding wound on said ferromagnetic core and connectedto the input circuit of said semiconductor device, said output windingbeing wound upon said ferromagnetic ,core in a direction to causecurrent flow through said input circuit of said semiconductor device ina direction opposite to current flow through said input circuit whensaid semiconductor device is in a conducting state whereby saidsemiconductor device is brought rapidly to a nonconducting state.

References Cited in the file of this patent UNITED STATES'PATENTS3,046,447 Kirk et 1. July 24, 1962

1. AN IGNITION SYSTEM FOR AN INTERNAL COMBUSTION ENGINE COMPRISING, ASPARK PLUG, AN IGNITION COIL INCLUDING A PRIMARY WINDING AND A SECONDARYWINDING, SAID SECONDARY WINDING BEING CONNECTABLE TO SAID SPARK PLUG, ASOURCE OF ELECTRICAL ENERGY, A TRANSISTOR HAVING AN EMITTER, A COLLECTORAND A BASE, SAID PRIMARY WINDING OF SAID IGNITION COIL, SAID SOURCE OFELECTRICAL ENERGY AND SAID COLLECTOR AND EMITTER OF SAID TRANSISTORBEING CONNECTED IN SERIES, MEANS CONNECTING SAID BASE OF SAID TRANSISTORWITH SAID SOURCE OF ELECTRICAL ENERGY FOR PROPERLY BIASING SAIDTRANSISTOR, MEANS CONNECTED IN CIRCUIT WITH THE BASE OF SAID TRANSISTORFOR INTERRUPTING CURRENT FLOW THROUGH SAID BASE, A FERROMAGNETIC CORE,MEANS CONNECTED IN CIRCUIT WITH SAID TRANSISTOR AND SAID SOURCE OFELECTRICAL ENERGY FOR SWITCHING SAID FERROMAGNETIC CORE FROM ONEDIRECTION OF MAGNETIZATION TO THE OTHER DIRECTION OF MAGNETIZATION INRESPONSE TO THE INTERRUPTION OF CURRENT FLOW THROUGH SAID BASE, ANOUTPUT WINDING WOUND UPON SAID FERROMAGNETIC CORE AND CONNECTED TO SAIDEMITTER AND SAID BASE, SAID OUTPUT WINDING BEING WOUND UPON SAIDFERROMAGNETIC CORE IN A DIRECTION TO CAUSE A CURRENT TO FLOW THROUGHSAID EMITTER AND BASE IN A DIRECTION OPPOSITE TO CURRENT FLOW THROUGHTHE BASE AND THE EMITTER WHEN SAID TRANSISTOR IS IN A CONDUCTING STATEWHEREBY SAID TRANSISTOR IS BROUGH RAPIDLY TO ITS NONCONDUCTING STATE.